Attic ventilation systems are typically used in residential buildings to provide proper ventilation of the attic space, which is desired to help prevent formation of condensation along the interior surface of the roof. Condensation can damage the attic insulation and the wooden structure of the building itself. Proper ventilation also helps to prevent premature melting of snow accumulated on a building roof, which can lead to the formation of ice on the roof that presents a safety hazard and can also lead to roof damage. Such attic ventilation systems will utilize vents placed into the underside of the soffit, which projects outwardly from the roof of the building and forms the overhang at the perimeter of the building roof. The intent of these attic ventilation systems is for air to travel through the soffit vents into the attic space and be discharged through an attic vent, which is typically placed at the apex of the roof.
The use of insulation in the attic to provide a barrier to the transmission of heat between the occupied portion of the building structure and the unoccupied attic portion of the building can restrict, or even prevent, the flow of air from the soffits to the roof vent at the apex of the roof. The insulation can be packed along the joists of the roof trusses to the soffits and not allow a passageway for the movement of air past the insulation into the portion of the attic above the insulation. Known construction of the insulation material can include cellulose, rock wool, fiberglass and expanded foam, the latter being used most often in manufactured housing, i.e. housing constructed in a factory and transported to the job site instead of being constructed at the job site. To maintain a discrete passageway for the movement of from the soffit, past the insulation barrier, and into the upper portion of the attic for discharge through the roof vent, baffle vents have been provided for attachment to the interior side of the roof to keep the insulation separated from the interior surface of the roof deck.
One embodiment of a baffle vent can be seen in U.S. Pat. No. 7,094,145, granted on Aug. 22, 2006, to Palle Rye, et al, and assigned to Brentwood Industries, Inc. The Rye baffle vent is stapled to the interior surface of the roof sheeting between the roof rafters and includes a tail portion that is bent in the vicinity of the soffit to extend from the interior surface of the roof sheeting to engage the wall plate. This baffle vent thus forms a barrier that prevents the movement of insulation into the soffit area and restricting the flow of air from the soffit into the attic. The structure of the baffle vent incorporates a series of convolution that are oriented parallel to the roof rafters to provide channels that define passageways for the movement of air past the insulation that is engaged against the baffle vent. In operation, the baffle vent utilizes the channels to keep the insulation away from the interior surface of the roof and establishes dedicated passages for the flow of air past the insulation along the interior surface of the roof sheeting.
Earlier configurations of baffle vents can be seen in U.S. Pat. No. 4,446,661, granted to Jan Jonsson, et al, on May 8, 1984, in which a corrugated sheet is fastened to the vertical surfaces of adjacent roof rafters to provide a plurality of longitudinally extending passageways for the movement of air past insulation in the roof. A major consideration in the design and manufacture of such baffle vents is the cost of such structures, particularly when taking into consideration the large square footage of the roofs of some residential buildings. Consequently, baffle vents have been fabricated extensively of foam or plastic material in narrow sheets that form self-supporting structures that can be handled and manipulated into position between the roof rafters for attachment against the interior surface of the roof sheeting. In U.S. Pat. No. 5,341,612, issued to Gary Robbins on Aug. 30, 1994, a baffle vent structure is formed of a thinner foam sheet material and includes a reinforced structure to prevent the vents from collapsing during shipping, handling and installation, as well as to prevent collapsing of the vents from compacted insulation which often is blown into attic areas of a building against the underside of the baffle vents.
Conventional residential construction affected at the job site will typically have the roof structure formed at the same time as the exterior shell of the building so as to get the building under roof to prevent the intrusion of foul weather into the interior of the building. The baffle vents described above are intended for use in such on-site construction techniques. Since the insulation is placed into the attic area long after the roof sheeting and shingles are added to the roof rafters, the baffle vents are formed to be placed between the roof rafters on the underside of the roof sheeting by attaching mounting flanged to either the vertical surfaces of the roof rafters, as is depicted in the aforementioned U.S. Pat. No. 4,446,661 to Jonsson, or the underside of the roof sheeting, as is depicted in U.S. Pat. No. 5,341,612 to Robbins. Generally, the baffle vents are installed as part of the installation of the insulation by contractors that specialize in the installation of insulation, rather than by the roofing contractor that will install the roof vent at the apex of the roof structure.
Manufactured housing is constructed in a factory setting where there is no pressing need to have the roof structure completed before the interior portions of the house are completed. As a result, the baffle vents can be installed on top of the roof rafters before the roof sheeting is fastened to the roof rafters. Generally, manufactured housing is formed with the interior drywall sheeting applied to the bottom side of the ceiling joists to form the inside ceiling of the housing before the roof is completed. The roof sheeting is then attached to the top surfaces of the roof rafters, followed by the application of the exterior roofing materials, typically fiberglass shingles. Insulation can then be installed between the joists on top of the drywall. While blanket fiberglass insulation or blown loose cellulose or fiberglass insulation can be used, expanded foam is often used in manufactured housing construction. The expansion rate of the foam places a substantial pressure on the baffle vent and will often collapse the passageways, resulting in the interruption of the air flow from the soffit past the insulation layer.
An example of a baffle vent that is adapted for use in the manufactured housing setting can be found in U.S. Pat. No. 5,596,847, granted to Michael Stephenson on Jan. 28, 1997. This baffle vent is formed with longitudinally extending ribs that are spaced on eight inch centers so that the single panel can be used on rafters whether spaced sixteen or twenty-four inches apart. A score line is formed on one of the interior ribs so that the excess eight inch strip can be removed if the baffle vent is used on rafters spaced at sixteen inched. In U.S. Pat. No. 4,096,790, issued on Jun. 27, 1978, to Laurence Curran, the baffle vent is formed to span across multiple roof rafters with a panel hanging down to engaged the wall plate and form a barrier to restrict the passage of insulation into the soffit area. In the Curran baffle vent configuration, mounting ribs are spaced at intervals corresponding to the roof rafter structure on which the baffle vent is to be applied. Thus, to be used with sixteen inch and twenty-four inch rafter spacings, the Curran baffle vent would have to be provided in two different models.
The Stephenson baffle vent configuration, and particularly in the Curran baffle vent configuration, the spacing of the longitudinally extending ribs provides a wide span between the ribs to define large passageways for the movement of air along the interior surface of the roof sheeting. Unfortunately, this wide expanse of unreinforced passageway, particularly when the baffle vent is manufactured from foam or a thin plastic material to maintain cost considerations, is subjected to collapse, especially when used with expanding foam insulation techniques. If the passageway collapses, the baffle vent is not functional to allow the passage of air from the soffit past the insulation layer to the upper portions of the attic structure.
Accordingly, it would be desirable to provide a baffle vent structure that would be particularly adapted for use in the manufactured housing industry to establish and maintain passageways for the movement of air from the building soffit past the insulation layer into the upper attic area for discharge from the attic through a roof vent. It would also be desirable that the baffle vent be formed in a manner to resist a collapsing of the air flow passageways when expanded foam insulation material, or other similar insulation material that exerts a force onto the baffle vent, is installed against the baffle vent.